1. Field of the Invention
The present invention relates to a plasma display device and a driving apparatus of the plasma display device. More particularly, the present invention relates to a driving circuit of a plasma display device.
2. Description of the Related Art
A plasma display device is a display device using a plasma display panel (PDP) that uses plasma generated by gas discharge to display characters or images. Such a PDP includes, according to its size, more than several hundreds of thousands to millions of pixels (discharge cells) arranged in the form of a matrix.
The plasma display device is driven during frames of time that are divided into a plurality of subfields, which are time intervals that each have a corresponding weight value. In addition, each subfield has a reset period, an address period, and a sustain period. The reset period is for initializing the discharge cells so that the next addressing can be stably performed. The address period is for selecting turn-on/turn-off discharge cells (i.e., cells to be turned on or off). The sustain period is for causing a sustain discharge for displaying an image on the addressed discharged cells.
When reset, address, and sustain operations are performed in their respective periods, capacitance is created on the panel because a discharge space exists between each pair of electrodes, including a scan electrode and a sustain electrode, and the discharge space operates as a capacitive load (hereinafter, referred to as a “panel capacitor”). Hence, reactive power is needed in addition to power for sustain discharge, in order to apply a waveform alternately having a high-level voltage (e.g., 5V) and a low-level voltage (e.g., 0V) during the sustain period. Therefore, the plasma display device uses a power recovery circuit for recovering the reactive power and re-using it to apply a sustain discharge pulse to the scan electrode or the sustain electrode.
A power recovery circuit operates by establishing a resonance path between a panel capacitor and a power recovery capacitor. A path starting from the power recovery capacitor to the panel capacitor may be used to increase a voltage of the panel capacitor. The opposite path, from the panel capacitor to the power recovery capacitor may be used to decrease the voltage of the panel capacitor. In a conventional power recovery circuit, when a switch or diode that forms part of the resonance path is damaged and thus short-circuited, the power recovery capacitor may be over-discharged or over-charged. For example, when a switch provided on the path through which the voltage of the panel capacitor is increased is short-circuited, a switch coupled to a ground voltage (0V) is turned on and the power recovery capacitor is discharged when the panel capacitor receives 0V. When, the power recovery capacitor is discharged to 0V, a power recovery operation cannot be performed. On the other hand, when a switch provided on the path through which the voltage of the panel capacitor is decreased is short-circuited, a switch coupled to a Vs power source is turned on and the power recovery capacitor is charged when the panel capacitor receives the voltage of Vs. Then, the voltage of the power recovery capacitor becomes too high to achieve power recovery.
As a result, current stress on the switch coupled to the ground (0V) or to the power source of voltage Vs may be increased, resulting in over-heating of the power recovery circuit that would cause smoke to come out of the circuit. Consequently, circuit elements of driving circuits other than the power recovery circuit may be damaged.